Values for rel und rev attributes

Dublin Core is one of the oldest metadata standards of the
WWW. Classic use cases
are limited to the html meta element. But
as already
Dublin Core: Expressing Dublin Core in HTML/XHTML
meta and link elements
states, Dublin Core is as well
applicable to the html link element.
The
microformats on the other side are specifying
attribute properties
mainly for usage within the body seciton
of an html document. But both ideas are very well combineable.

Clarification

as already stated at Dublin Core,
the notation of the attribute properties is:

DC.attributeproperty

This means: Uppercase "DC", period, then the attribute property in
lower case. Using these attribute properties means to exactly
follow this notation. If necessary, this implies a slightly more complex
notation in CSS stylesheets:

p[class="DC.description.abstract"] { ... }

Main focus of this specification is not, how to style these elements,
but how to logically and semantically markup appropriate content.

DC.title

Document title

The usage in the head section
is redundant and should be avoided. These two notations
have the same meanings:

titlePage title/titlemeta name="DC.title" content="Page title"

Since it is already necessary by specification to include the
title element, this notation is preferred.
But it is possible to extract the contents of the
title element
to xml (rdf) as
dc:title.

Useful is, using this attribute property within the
body section.
In most cases there will be some headlines. One of them may
be the official title of the document. This may be
identical to the
title element, but not necessarily
has to be. Possible locations for this title might be
the first headline
(h1)
or may be another headline. For example imagine a page,
where the first headline contains a company or website
name like a banner, followed by a headline which then is
the pages title:

bodyh1FooBar Ltd./h1h2Our Products/h2
...
/body

To unambigeously mark the appropriate headline as the title
you may add the Dublin Core attribute property. ID is preferred,
since a page should have only one title:

bodyh1FooBar Ltd./h1h2 id="DC.title"Our Products/h2
...
/body

DC.creator

Denotes a
person or
group mainly responsible for
this resource. For text documents the meaning is
identical to the
author
attribute property. Other types of creators may be (among others)
artists, photographers or illustrators

The first line shows the classical usage within the
im meta element. This does not specify
the format of the "content" attribute. It may contain plain text,
a URL or anything else. Best practice is embedding the
full name as plain text.
The second line shows the usage within the
link element. Here it is clearly
specified that the href attribute can only contain a URL.
So the attribute property can only be a link to a web resource
(web page) where we can find information about the
creator. This notation is preferrable in all cases where
we have a URL. Of course it is possible without problems
to combine both notations.

Using this in the
body is interesting. As with the
XFN microformats
it is possible to use this attribute property in a very similar
way. First an example according to
XFN:

This page was made by a href="http://www.rorkvell.de/impressum" rel="me"me/a.

The usage of "me" implies roughly that the target person is
the one who created this page. More precise but else
syntactically identical this is possible with
Dublin Core:

This page was made by a href="http://www.rorkvell.de/impressum" rel="DC.creator"me/a.

Studying
hCard
it is self-evident using this property within hCard in much the same
way as XFN:

More interesting is the usage within the
body section. Here we may mark up
keywords or key phrases at any location. Usually the
best element for this is
the span element,
but any kind of headline would be a good choice, too:

This is about span class="DC.subject"metadata/span,
especially the usage of span class="DC.subject"Dublin Core/span
attribute properties and their usage in span class="DC.subject"xhtml/span.

DC.description

A textual
description of the content,
including a summary,
an abstract or
teaser. For images, movies or similar my
contain a description of the content.

Usage in the head is redundant.
There also exists the more known "description". So in the
head section only one of these
variants should be used (they are equivalent):

meta name="description" content="Description of the content"meta name="DC.description" content="Description of the content"

DC.description.abstract

Usable as class name or ID for a paragraph
containing a summary, foreword, abstract
or teaser:

The usage is the same as in
hCard
combined with
XFN,
just that instead combining with
XFN, it
is combined with
Dublin Core.
The statement is somewhat more precise than
XFN.
Since most commonly there will only be one publisher, as with
DC.creator,
this construction would be pretty legal, too:

It should be specially noted that this way it is
possible to precisely define the roles of the different
persons which have address records in a web resource.

DC.date

Date of creation, modification or validity date.
This is mostly similar to
hCalendar, but explicitely
defines dates related to this resource. The common
hCalendar markup thus may be simply
expanded (not replaced) by these properties.

DC.date.created

Date of creation.

DC.date.valid

Date, until this document is still valid.

DC.date.available

Date range where this document will be or was available.

DC.date.issued

Date this document was issued.

DC.date.modified

Date this document was modified.

If using in the
head section the date is
noted in the format YYY-MM-DD. This is the same
as defined at
hCalendar
as title attribute property for the
abbr element.

DC.type

Type or
role of the document (f.ex. homepage,
poem, working paper, directory). The type should
be selected from the
Dublin Core vokabulary.
Not to be confused with the html attribute type, which
contains the mime type!

The usage in the
body is not trivial, since
DC.type as such cannot be used as class name or id on its own.
This classname or id may be used if the content of the element
is made of one of the words from the
Dublin Core vokabular.
Or, if the content is not exactly the word or is the
word in another language, the exact word from the
vocabulary may be added as the title element of the
html container.

DC.format

This should contain the mime type. Since in html this is
already done with the type attribute, or in the
http header or in the html header in the
meta element.
On the other hand all these attributes may be exported to
xml (rdf) as dc:format

DC.identifier

This is most useful in the
head section as property for the
rel attribute of the
link element. Similar to
base this link does not add the extra
functionality of base:

This is the full identifier of the current document in the
english xhtml version.

DC.source

Points to a web resource which is the source for the current
content or where the current content is based on or which gave
the ideas to to current content. Or the current
document may be a translated version of the source.

DC.language

This is redundant in the head
as well as in the body and
so should be avoided. In html the same is achieved
by the "lang" attribute, regarding parts of the current
document, or by the "hreflang" attribute,
specifying the language of the target attribute. In
xml and xhtml documents this is specified by the xml:lang
attribute,

DC.relation

For styting relations it is better to use the html
rel and rev attributes. On the other hand it is
possible to export the content of these attributes
dc:relation in xml (rdf).

DC.coverage

this makes a statement about the spatial or temporal
validity of the document. In case of spatial
limitations this document is only valid for some specified
region. The temporal validation may be used for documents
about history.

This is mostly useful in the
meta element, regarding the
current document.

DC.rights

The meaning is identical to the nowadays more widespread
rel="license" and may be
used alternatively.